This specific objective is prett hard, but there are 2 main ways to do it.

1: take heavy tanks and just advance constantly, dont stop. It takes a lot of micro to do it, but with a little training u can do it.

2: just take helicopters, take them around the right side of the map and kill the commander in the final sector. This also can be tricky because the path you are gonna use is pretty narrow. So just try it a couple of times, since no approach will take more than 10 minutes it should go quite well.

If u still have trouble go and search on youtube, Hob Gadling made a walkthrough for the campaign, u will have to Pm him i think since i dont remember the name of the channel.

@ FLX: he ment: i completed it in 32 minutes, but i just cant get under 32 minutes.